What is the rate-limiting enzyme of glycolysis?

The rate-limiting enzyme of glycolysis is phosphofructokinase-1 (PFK-1). This enzyme catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, and it is tightly regulated by the levels of ATP, AMP, and citrate. High levels of ATP inhibit PFK-1, slowing glycolysis, while low levels of ATP (or high levels of AMP) activate it, speeding up the process.